1. Field of the Invention
The invention relates in general to a testing technology for a computer system, and more particularly, to a signal processing system with a built-in self-test (BIST) function.
2. Description of the Related Art
Ensuring normal functionality of products when the products are shipped out of the factory is always a focus of manufacturers. By pre-filtering out and repairing problematic products, post-sales returns and exchanges can be effectively prevented to increase customer satisfaction.
For an electronic system, a most common test item is inputting a simulation signal at an input end of a circuit and monitoring whether a processed result outputted at a rear-end is correspondingly a correct output signal. Taking a communication system 100 simultaneously including a transmitting circuit 12 and a receiving circuit 14 in FIG. 1 for example, a current testing method is establishing a loopback path 16 between the transmitting circuit 12 and the receiving circuit 14. In a normal mode, the loopback path 16 is set as open circuit, so that the transmitting circuit 12 and the receiving circuit 14 operate independently. In a testing mode, the loopback path 16 is set as close circuit, such that the signal processing module 18 controls the transmitting circuit 12 to provide a testing signal 13 via the loopback path 16 to the receiving circuit 14. According to a response signal 15 outputted by the receiving circuit 14, the signal processing module 18 determines whether the transmitting circuit 12 and the receiving circuit 14 are functional.
An advantage of the architecture shown in FIG. 1 is that no additional signal source for providing the testing signal is involved, and thus costs of testing apparatuses can be reduced. However, the testing architecture in FIG. 1 is unsuitable for applications of several signal processing systems below: 1) a signal processing system in which a dynamic output range of a transmitting circuit is different from that of a receiving circuit; 2) a signal processing system that does not allow simultaneous operations of a transmitting circuit and a receiving circuit; 3) a signal processing system in which a coupling path between a transmitting circuit and a receiving circuit is strictly prohibited; and 4) a signal processing system that includes only a receiving circuit but not a transmitting circuit.
For the above situations, a simulation input signal usually needs to be externally provided from a testing machine to test whether a receiving circuit is normal. However, signal frequencies to be processed by front-end circuits in many signal processing systems (e.g., a wireless communication apparatus) are quite high. As costs of testing apparatuses that can generate high-frequency testing signals are very high, overall testing costs are inevitably increased by considerable amounts.